Tech

iTrader: (1)

I'm posting this for another person...

He picked out this combo thinking he wouldn't have to notch the pistons or mill the head. The guy installing the stuff saw your post saying that DCR is going to cause problems at low rpm because of the large amout of overlap. The guy installing it wants to mill the head but won't flycut with the pistons in the shortblock. He says a $1200 rebuild with forged slugs is the only way to go with the G5x3. My buddy is already over budget with the AFR/G5x3/FAST 90/NW 90/85mm MAF/42#injectors and doesn't want to put the money in forged pistons. He has a Yank 4400, 4.10s and mods listed above (minus G5x3 now). Oh yeah... the car is torn apart and he has 4 weeks to get it on the road before a NFME in Memphis. The sponsor he bought the package from said to put the heads on unmilled and 'let er eat.'

Does it really matter if his DCR is lower at sub 3k rpms? He has a huge converter and is only in that range while cruising.

If this is such a silly idea, why are so many people posting 460+rwhp numbers with untouched AFR heads and this setup? He wants mid to low 11s out of it (full weight).

Thanks Tony.

Tony Mamo @ AFR

iTrader: (13)

Guys....

Combinations are a very "personal" thing. I dont have a problem with running a sizable cam in a weekend warrior, I would simply want to compliment it and make it a much better OVERALL package by increasing the CR. Think about what I have said in some other threads....You could have the same peak HP (or very similar) with a slightly smaller cam with more CR and have more area under the power curve, better low speed driving manners, more midrange punch, better idle quality (if you consider that a plus....lol), and a little better fuel economy. Thats the direction I would choose....OR, I would go ***** out at 11.5 CR, Torco at track day or a splash or race gas, and then put an X3 cam or something similar in it.

Tell your friend good luck and hopefully he will be pleased with the results....it sounds like his car is more set up to tolerate the type of power band that combination will likely provide so he should be in good shape.

Tech

iTrader: (1)

So you are saying leave the heads unmilled and slide the bumpstick in? How much power is in question here? For max effort, I could understand doing what you said but JUST like you said... this is a weekend warrior.

What is generally acceptible for PtoV clearance on an automatic car? 80-100 thousandths?

prostock_bigblock

iTrader: (11)

wish him a good luck ...... he must focus on the 10s with this combo..

01_SuperSlow

iTrader: (7)

I would talk to LG about this, since they have put out many of these combos with great results.

Tech

iTrader: (1)

We have talked to LG. They said mill the head .049 and flycut. The engine builder will NOT cut the pistons in the block.

Wasn't this cam built for stock heads? Then why the hell do you have to mill AFRs to make it work?? This is so frustrating. That cam is causing more damn headaches. Everyone we speak to give us a DIFFERENT answer.

Here are the important questions that we need answered..

Will the PtoV tolerance likely be within an acceptible range? It will be clayed on his car to verify. What IS acceptible? .080? .100?

How much power is left on the table? As a rule of thumb, you lose 3% of power for every 1 pt drop in compression. How terrible is the DCR going to be from 1500-2500 rpms?

Could all of these headaches be prevented if we knew the IO and EC specs?

Brian Tooley Racing

iTrader: (13)

I would say your dealing with about .050" clearance, .040" is minimum, and if your engine builder won't fly cut your pistons, send it to someone who will.

We have had Ford engines that we fly cut the pistons for Twisted Wedge heads run for up to 8 years and no problems.

PREDATOR-Z

From what I've seen, AFR's have a ~.015 more clearance than stock heads. So you could still mill those heads a little with a 114 lsa G5X3 without notching pistons.
This should give you a little more DCR with stock gasket (although not ideal for quench).

What I would do is first choose your gasket for your desired optimal quench and do your calculations from there.

All this is theoretical untill you degree and use a dial indicator for a moc up install PTV check.

Tech

iTrader: (1)

The gaskets we have were supplied from TTP. They are the GM steel.

PREDATOR-Z

GM MLS, but what thickness compressed. This will able you to determine your quench which is as much if not more important than CR.
Take Gasket thickness compressed - piston out of hole = quench.

I like .035>.038 quench but some poeple will run as low as .030>.033

BTW is your cam 112 or 114 ???

Anyways this is how I would go about it:

1- determine my piston out of hole (or in, in some cases) and calculate my quench (choose gasket)
2- Moc up install and PTV measurements.
3- based on my results, then see if there is room to mill.


As Tony stresses all the time, COMBO is the game. I was able to make 404rwhp cam only with a 224/220 cam. That was done by some head port matching (intake/exhaust), and proper quench.
5rwhp here, 5rwhp there and it all adds up.

Tech

iTrader: (1)

I can get you a part number but I can't tell you the compressed gasket thickness. This combo was sold as a set from TTP. If there is a place to cross reference a part number with thickness, please point me to it.

The cam is ground on an 112. Before buying all the parts he asked for help in this very section of LS1tech as to which LSA to get. Everyone said 112.

There is no doubt (NOW) that this is not an optimal combo for a max effort car. NO DOUBT. Unfortunately, all of the band wagonning and dyno numbers may have lead to misinformation. Everyone has a different theory.

This car isn't for NHRA or Nascar. It's a weekend warrior car that sees street time on nice days. People and sponsors on this board told him he was an idiot for running a Yank 4400 on the street. With mail order tuning, the car drives without any quarks other then it pisses off the neighbors.

Brian Tooley, did you say that there will only be ~.050 of clearance with this cam or that ~.050 is considered acceptible for a hydrolic lifter car?

PREDATOR-Z

The G5X3 on a 112 will fit a stock headed car but that is with insane clearances.
The AFR will give an extra ~.015 room.
So forget about milling without notching and just concentrate about getting the proper Cometic gaskets to put you in the optimum quench range.

I think that a 0.045 Cometic will do and is is much better than the GM MLS wich I believe is .054 or .052 (can't remember which.)

Proper quench on AFR's go a long way. AFR's got a double quench area instead of just 1 like stock.

Tech

iTrader: (1)

Please define 'insane.'

If the cam will fit under the untouched AFRs in an automatic car and make the power that is advertised (460rwhp+ w/ all the bolt ons and FAST 90/90), then the owner will be happy.

PREDATOR-Z

Insane is anything less than .070 on a daily driven car.
Yes you can go lower but "kissing " is much more evident.
That is MY opinion.

Look, be wise and do it properly, but keep some caution as to what your car will be used for. Leave some room for error.

Do not let all those dyno #'s mess you up.

Tech

iTrader: (1)

No offense intended Pedator, but didn't you just sorta brag you got 400+rwhp out of a Stealth cam.

I'm not an idiot and have been around cars enough to know that dyno numbers are not the absolute measurement of viability of a given engine. Let's not dwell on that. OTOH, if the cam/head combo is off other identical setups (except they were milled and flycut) mark by 20 hp between his shift extension and redline, there is gonna be one pissed off f-body owner.

There is nobody in St. Louis, MO that I know of who is flycutting LSX based engines. Specifically, the car is in a certain mechanic's garage now and he won't do it.

Ok, fellas (and possibly gals)... what PtoV clearance is safe for a street car? Anybody else have input?

Nate_Taufer

iTrader: (1)

.080" on the intake and .100" on the exhaust is always the rule of thumb i go by and have never had a problem.

Nate

kumar75150

whats the deal with people afraid to flycut pistons?

Tony Mamo @ AFR

iTrader: (13)

I don't know but I run into it ALL the time at AFR....Its part of the process if you plan on running a big cam in a stock short. With all the X3 cars that leave LG, I think Lou can do it while sipping on his favorite cup of Starbucks coffee....

MUSTANGEATER

iTrader: (10)

Well I wouldn't say there isn't anybody in St. Louis who has flycut, I've got 8 cut slugs myself and even with Nitrous no problems. If you need the isky tool let me know I'd be more than willing to lend a hand....

Also you gotta think about what happens to your quench and clearance when your motor warms up... A lil "Engineer talk" here


Think about what the effective quench on an Iron motor is then think about an Alum LS1 motor....


If it was my car I'd angle mill the **** out of the 205's and cut cut cut....

MUSTANGEATER

iTrader: (10)

I've gotta see this Starbucks and fly cutting